Tunable device for extracting radio frequency energy from a power line



July 26, 1960 J. BEEVER ETAL 2,946,883

TUNABLE DEVICE FOR EXTRACTING RADIO FREQUENCY ENERGY FROM A POWER LINE FiI'ed Sept 25 1959 INVENTORS JACK v BEEVER WALTER GOODMAN 7% MM ATTORNEY 2,946,883 Patented July 26, 195i} Un rr d Ofice TUNABLE DEVICE FOR EXTRACTING RADIO FREQUENCY ENERGY FROM A POWER LINE Filed Sept. 25, 1959, Ser. No. 842,246 7 Claims, Cl.'25 -.-1'6) This invention relates to a device for extracting radio frequency energy from power wiring feeding television, and FM receivers in homes, institutions, industrial establishments and the like.

Any conductor, such as power wiring, under the influence of radio frequency fields will have induced in it currents whose frequency will be the same as that of the inducing fields. The power wiring, upon energization by an intercepting wavefront, will behave as a transmission line of the uniconductor type. Currents flowing along these lines will see no absorbing loads, since outlets or appliances connected to these outlets are merely ends of the line. From these points radio frequencyenergy will reflect, producing another wave of current passing in an opposite direction to the incident wave. The'passing of these currents will produce standing waves along the line, stationary points of reinforcement ofcurrent and of cancellation. 1 v

The primary object of the invention is to provide a device electrically connected to the antenna terminals of a receiver which may be capacitively mounted on a power cord feeding the receiver and readily adjusted thereon to select the position on the cord Where thedesired radio frequency energy shows 'a point of reinforcement.

Another'object of the invention is to provide a tunable device for extracting radio frequency energy from power wiring feeding a receiver wherein the operator can readily and easily select points of different quality rather than simply selecting for strength of signal. For example, in television reception, multipath signals produce ghosts. It frequently happens that a point on the cord exists where the ghost signal is cancelled by a reflected wave, leaving the prime signal still present. The instant device can correct these ghost images.

Another object of the invention is to provide a tunable device of the character described which is provided with an easily operable means for. mounting the same 'on the power cord and which is so constructed that the same' can be readily slid along the cord and there frictionally retainedin a desired selected position.

Another object of the invention is to provide a tunable device of the character described which is compact, attractive and unobtrusive as compared .to the conventional indoor television antenna and which is less prone to disturbance by" them'ovements' of people in the general vicinity of the antenna.

These and other objects of the invention will become more apparent as the following description proceeds in conjunction with the accompanying drawings, wherein:

Figure 1 is diagrammatic perspective view illustrating the application of the device;

Figure 2. is a perspective view of the device looking towards the front thereof;

Figure 3 is a plan view of the dewce with the cover removed;

Figure 4 is a sectional view taken on the line 4-4 of Figure 3;

pose later to appear.

' put.

Figure 5 is a sectional view taken on the line 6-6 of Figure 3; and

Figure 6 is a perspective view of a feature thereof.

Specific reference is now made to the drawings wherein similar reference characters are used for corresponding elements throughout.

Although the instant device was designed and constructed to extract radio frequency energy in the VHF spectrum, 54 to 216 megacycles covering. TV and FM, the device will be described in connection with TV Indicated generally at 10 is a conventional TV receiver equipped with antenna input posts 12 and a power line or cord 14 (generally consisting of two conductive wires in an insulating sheath) carrying a plug 16 .insertable in a wall socket or receptacle 18. The present tunable device is indicated at 20 and is adapted to .be mounted on the line cord 14 and to be slid therealong and be retained thereon, frictionally, in a selected position for best extraction of radio frequency energy from the cord after the terminals 22 carried at the ends of a length of conventional. antenna Wires 24 are connected to the antenna input posts. 12, one of the antenna wires'being electrically connected at its other end to the elongated conductive member. in the device as will appear more fully hereinafter.

The device is in the form of an elongated housing made of an insulating material, such as a suitable plastic, comprised of a rear member 26 and a cover. member 28. The device is preferably six inches long to allow for extraction of radio frequency energy in the VHF spectrum of 54 to 216 megacycles in' power lines in common'urban use. e

The rearmember includes a base wall 30 and a pen ripheral wall 32 thereabout havingan opening 34 adj'acent the tapered .end thereof and a cut-out portion 36 intermediate the ends of one side thereof. The wallp30 is formed with a central longitudinally extending channel bar 38 which is positioned within the base member, the channel barthereby providing a longitudinal groove 40 opening through the base wall 30. The groove also opens through the peripheral wall. 32 at longitudinally aligned ends thereof as is evident from Figure 2.

Positioned on and coextensive with thepbar 38 is a conductive or metallic channel member 42 which is provided adjacent its ends with upstruck lugs 44 for a pur- Adjacent the lugs, the conductive channel member 42 includes upstruck cars 46, one of which grips one of the wires 48 of the antenna wires 24 to make electrical contact with the conductive channel 'member 42. For further security, it is preferred that 'theears be provided in pairs so that the other ear of a pair grips the insulation 50 of said antenna wire 48, the other antenna wire being out of contact with the conductive channel member 42. As illustrated, two antenna wires are employed for the usual television receiver with dual or balanced antenna inputs. It should be understood that a single antenna wire may be employed for connection to,receivers with an'unbalanced antenna in- In order to minimize the possibility of dislodging the antenna wire 48 from the conductive channel 42, a pair of laterally spaced lugs 51 are-provided which extend upwardly from wall 30 adjacent the channel about which the antenna Wires are curled to provide a tortuous path.

A means is provided to frictionally retain the line cord 14 longitudinally in the groove 40 of the housing so that the device may be slid along the line cord and automatically retained in the selected adjusted position where the desired radio frequency energy shows a point of reinforcement or the best position with respect to quality and strength of signal. This means comprises a member in the form of a door 52 coextensive in length and width with said groove 40 and hinged to the housing in position to close off said groove and apply frictional pressure on the line cord therein by reason of a longitudinal central rib-'54 extending. vertically therefrom. The hinging is effected by providing spaced, arcuate hinge lugs 56, 58 and 60 which extend into slots 62, 64 and6 6 respectively in the wall 30 of the rear member along the length thereof and adjacent the plastic bar 38, the arcuate portions of the hinge lugs movably bearing against the edges of said slots.

A finger pressure means is also provided to operate said grip member 52 as follows. The central hinge lug 58 is larger than the end hinge lugs 56 and includes a grooved lip 68. A spring in the form of a wire 70 is engaged in .the grooved lip 68 intermediate its ends. Upstanding from the wall 30 and extending laterally thereof are plates 72 and 74 having notches opening through their upper ends to receive the wire 70, there being a further plate 76 adjacent the tapered end of the housing to limit endwise movement of the spring wire. The wire retaining notches in the plates 72 and 74 are so located as to apply tension on the spring wire whereby the member 52 is normally urged into a closed gripping position towards the groove 40 holding the line cord 14. To releasably urge the grip member 52 into an open position, a depressable member 78 is provided in the form of an angulated button which is pivoted at one of its ends for movement around a vertical axis in the housing, the other end of the button including a portion 80 adapted to bear against the central hinge lug 58, when the button is depressed, and pivot the grip member 52 into an open position against action of the spring wire 70 as shown in dotted lines in Fig. 5.

The cover member 28, which is coextensive with the rear member 26 is sealed to the rear member along the edges of both members preferably with tongue and groove connections between them as indicated in the drawings. Toefiect the pivoting of the button 78 in the housing, the wall 39 and cover 28 are provided with vertically aligned recesses which receive opposed detents 82 and 84 at one end of the button 78. The upstanding lugs 44 adjacent the ends of the conductive channel bear against the inner surface of the cover 28 when the latter is sealed in place on the rear member 26 to prevent vertical movement of the conductive channel in the housing.

In use, the terminals 22 are connected to the antenna input posts 12 of the receiver It The finger piece or button 78 is depressed and with the closure member 52 in the open position, the line cord '14 feeding the receiver is laid into the groove 40 along the length thereof. Then the button is released, whereupon the member 52 closes and the rib 54 thereof exerts frictional gripping pressure on the length of the line cord in the groove. The device is then moved along the line cord until the selected position is found for the best signal reception.

Although a preferred embodiment is here shown and described, skilled artisans may make minor variations without departing from the spirit of the invention and the scope of the appended claims.

We claim:

1. A tunable device for extracting radio frequency energy from power wiring feeding a receiver comprising an elongated housing of insulating material, a longitudinal conductive channel carried by said housing, means to slidably and frictionally clamp the power wiring in said housing along the length of said channel in proximity thereto and a conductor electrically connected at one of its ends to said channel and adapted to be connected at its other end to the antenna input of the receiver, said means including a member substantially coextensive with said channel hinged to said housing, and spring means normally urging said member towards said channel and against the power wiring in said housing.

2. The combination of claim 1 and depressable means carried by said housing operative against action of said spring means to urge said member to an open position away from said channel.

3. The combination of claim 2 and a longitudinal rib on said member adapted to frictionally engage the power wiring and clamp the latter in said housing.

4. A tunable device for extracting radio frequency energy from power wiring feeding a receiver comprising an elongated housing of insulating material, one wall of said housing including a longitudinal channel bar upstanding -in said housing forming a longitudinal groove opening through said one wall, adapted to receive the power wiring, a conductive channel mounted on said bar, a longitudinal member hinged along one of its sides to said housing, spring means in said housing urging said longitudinal member against said housing to close oif said groove and frictionally grip the power wiring therein, and a conductor electrically connected at one of its ends to said conductive channel and adapted to be connected at its other end to the antenna input of the receiver.

5. The combination of claim 4 and a longitudinal rib on said longitudinal member adapted to frictionally engage and clamp the power wiring in said groove.

6. The combination of claim 4 and a, button pivoted in said housing having a portion therein adapted to press against a portion of the longitudinal member in said housing and urge said longitudinal member into an open position against action of said spring means away from said groove when said button is depressed.

7. A tunable device for extracting radio frequency energy from power wiring feeding a receiver comprising an elongated housing of insulatingmaterial, a longitudinal conductive channel carried by said housing, means to slidably and frictionally clamp the power wiring in said housingalong the length of said channel in proximity thereto and a conductor electrically connected at one of its ends to said channel and adapted to be connected at its other end to the antenna input of the receiver, said means including a member substantially coextensive with said channel hinged to said housing and releasable means retaining said member in a position to close said channel with a portion of said member frictionally engaging the power wiring in said housing.

References Cited in the file of this patent UNITED STATES PATENTS 1,676,404 Mauborgne et al. July 10, 1928 2,485,264 Ebbeler Oct. 18, 1949 2,581,983 Thompson Ian. 8, 1952 

